Note: Descriptions are shown in the official language in which they were submitted.
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TITLE OF THE INVENTION
METHOD OF AND APPARATUS FOR INSPECTING BOTTLE OR THE LIKE
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method of and an
apparatus for inspecting a bottle or the like using an
optical device to determine presence or absence of a
defect by electronic processing.
2. Description of the Prior Art
Various methods of optically inspecting a bottle
or the like to determine presence or absence of a defect
such as, for example, a split called check or a foreign
article such as a stone or the like which may appear at
or mixed in a bottom or body portion of the bottle are
conventionally known. An exemplary one of such methods
is disclosed, for example, in Japanese Patent
Publication Application No. 58-58020. According to the
method, light is irradiated in an inverted conical ring
shape upon a circumferential side wall of a bottle for
inspection from above from a light pro~ecting section
such that it may be introduced toward a bottom face of
the bottle so as to reach a corner material portion of
the bottom through the material of the side wall of the
bottle, and reflected light which is reflected, where
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there is a split in the corner material portion, from
such split ls introduced into a single photoelectric
transducer element to detect such split.
With the method, however, the optical system is
complicated in construction, and besides, since
reflected light is detected only by means of the single
photoelectric transducer element, if the angle of light
reflected from a check is different only a little from a
specified angular range, such reflected light will not
be introduced into the photoelectric transducer element,
and consequently, presence or absence of a defect cannot
be detected accurately. Further, various design
patterns are commonly formed on bottom faces of bottles,
and the amount of reflected light is varied to a great
extent depending upon such design pattern. Accordingly,
it is impossible to detect a check of a bottle only from
a variation in amount of light when the bottle has a
design pattern thereon.
Another exemplary one of such conventional
methods as described above is disclosed in Japanese
Patent Laid-Open Application No. 61-107144. According
to the method, a bottle is carried in to an inspection
position in the neighborhood of a one-dimensional image
sensor, and while the bottle is being rotated around an
axis thereof with the axis thereof held in parallel to a
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longitudinal direction of the image sensor, it is
illuminated such that an image of transmission light
through the bottle is formed on the image sensor. The
image sensor is scanned so as to obtain a set of
signals, and such scanning is repeated during rotation
of the bottle so as to successively obtain a plurality
of sets of signals. Two sets of signals obtained at a
first rotational position of the bottle and a second
rotational position of the bottle after rotation of the
bottle from the first rotational position are compared
with each other, and presence or absence of a defect is
determined in accordance with a result of such
comparison.
With the method, the accuracy in detection is
somewhat higher than that of the former method described
above. However, while employment of a one-dimensional
image sensor is more advantageous in regard to
resolution than employment of a two-dimensional image
sensor, a high degree of accuracy cannot be anticipated
for detection of a check of a bottle using a one-
dimensional image sensor since the direction of
reflected light from a check of a bottle is changed to a
great extent by rotation of the bottle and since such
check is various in shape and further since disturbance
light from other than such check is received much by the
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one-dimensional image sensor due to rotation of the
bottle. Accordingly, the latter method cannot cope
efficiently with checks of bottles having various
shapes.
SUMMARY OF THE INVENTION
It is an ob3ect of the present invention to
provide a method of and an apparatus for inspecting a
bottle or the like by which presence or absence of a
defect, particularly of a check, can be determined with
a high degree of accuracy.
In order to attain the ob~ect, according to an
aspect of the present invention, there is provided a
method of inspecting an ob~ect for inspection such as a
bottle or the like being rotated or moved at a
predetermined speed to detect a defect of the ob~ect,
which comprises the steps of irradiating light upon an
inspection area of the ob~ect being rotated or moved,
photographing reflected light from the inspection area
of the ob~ect by means of a two-dimensional camera which
includes solid-state image pickup elements, fetching
picture element data for a first frame at a first point
of time from the two-dimensional camera and storing the
data into a memory, fetching picture element data for a
second frame at a second point of time after a fixed
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interval of time after the first point of time,
calculating differences of the picture element data for
the second frame from the picture element data for the
first frame from the memory, binary digitizing the
differences with reference to a predetermined brightness
threshold level, counting a number of those of the
differences which have one of two binary values, and
comparing the count number with a predetermined number
to determine presence or absence of a defect in the
object for inspection.
In case the obfect for inspection is, for
example, a bottle and has a check as a defect, since the
direction of reflected light from the check is
instantaneously changed to a great extent by rotation or
movement of the bottle, even if picture element data
originating from such reflected light are fetched at a
certain point Tl of time from the two-dimensional camera
as a picture element at a certain position, picture
element data originating from reflected light of the
check are not fetched at another point T2 of time after
the predetermined interval of time. On the other hand,
since disturbance light from any location other than the
check is reflected almost in the same direction also
after some rotation or movement of the object, picture
element data are fetched at both of the points T~ and T2
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of time.
Accordingly, if differences are taken between
picture element data for one frame fetched from the two-
dimensional camera at the point Tl of time and picture
element data for another frame fetched at the point T2
of time after the predetermined interval of time after
the point T~ of time, then picture element data of high
brightness values originating from reflected light from
the check remain, but picture element data originating
from disturbance light from any other portion than the
check are cancelled. Thus, such differences are
subsequently binary digitized or divided into two groups
of white and black with reference to a predetermined
brightness threshold level, and a number of those
picture elements having those of the differences which
have one of two binary values is counted. Then, when
the count number is greater than the predetermined
number, it is determined that there is a defect in the
ob;ect. Consequently, presence or absence of a check
which makes a defect can be detected with a high degree
of accuracy.
If the speed of rotation or movement of the
ob~ect changes, then also the direction of reflected
light from such check is changed and the amount of
incidence light to the two-dimensional camera is
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changed. Accordlngly, preferably the fixed lnterval of
tlme between frames at which picture element data are to
be fetched and the brightness threshold level for binary
digitization are ad~usted in response to a speed of the
ob~ect for inspection ln order to lmprove the accuracy
in detection. Consequently, when data for each one
frame from the two-dimensional camera are to be fetched
at a high speed, the number of frames to be thinned out
is ad~usted in response to the speed of rotation or
movement of the ob~ect.
Preferably, a number of those of the dlfferences
whlch have one of two blnary values is counted for each
of a plurality of window areas included in a
photographlng area of the two-dlmensional camera in
order to except such picture elements origlnating from a
design pattern formed on the ob~ect for inspection. The
two-dimensional camera can thus detect presence or
absence of a defect of the ob~ect for inspection with a
high degree of accuracy for the plurallty of locations
of the ob~ect without detecting a design pattern or the
like as a defect in error.
According to another aspect of the present
invention, there is provides an apparatus for inspecting
an ob~ect for lnspectlon such as a bottle or the llke
being rotated or moved at a predetermined speed by a
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handling machine to detect a defect of the ob~ect, which
comprises a light pro~ector for irradiating light upon
an inspection area of an ob~ect for inspection being
rotated or moved, a two-dimensional CCD (charge-coupled
device) camera for photographing reflected light from
the ob~ect only for a fixed area, a camera controller
for successively fetching picture element data produced
from the two-dimensional CCD camera for each one frame
after each predetermined interval of time and storing
the thus fetched picture element data therein, a
difference calculating section for calculating
differences between the picture element data thus
fetched for different frames, a binary digitizing
section for binary digitizing the thus calculated
differences with reference to a predetermined brightness
threshold level, a counter for counting a number of
those of the differences which have one of two binary
values, and a main controller for ad~usting the
predetermined interval of time for the camera controller
and the predetermined bright threshold level for the
binary digitizing section in response to a speed signal
from the handling machine representative of a speed of
the ob~ect and for counting a number of those of the
differences which have one of two binary values and
comparing the count number with a predetermined number
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to determine presence or absence of a defect in the object
for inspection.
With the apparatus, presence or absence of a
defect in an object for inspection can be detected with a
high degree of accuracy with a minimized influence of
disturbance light.
The apparatus may further comprise means for
causing the counter to count a number of those of the
differences which have one of two binary values only for
one or ones of a plurality of window areas included in a
photographing area of the two-dimensional CCD camera which
is or are designated by the main controller.
Preferably, the apparatus further comprises a
monitoring display apparatus for reproducing and displaying
thereon data for a frame fetched by the camera controller
so that setting for inspection can be performed
appropriately and readily while a condition of a defect is
being observed.
Accordingly, in another aspect the present
invention resides in a method of inspecting a moving object
for detecting a defect in the object, comprising the steps
of irradiating light upon an inspection area of the object
from an angle between a line exte~;ng perpendicular to a
rotational axis of the object and the rotational axis of
the object, photographing reflected light from the
inspection area of the object by a two-dimensional camera,
storing picture element data corresponding to a first frame
at a first point of time of the photographed reflected
light into a memory, storing picture element data
corresponding to a second frame at a second point of time
of the photographed reflected light after a fixed interval
of time after the first point of time, said fixed interval
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of time being determined based on a predetermined period of
time and a thinning out value that is determined based on
a rotating speed of the object, calculating differences of
the picture element data between the first and second
frames, binary digitizing the differences with reference to
a predetermined brightness threshold level, counting a
number of the differences which have one of two binary
values, and comparing the count number with a predetermined
number to determine the presence or absence of a defect in
the object.
In a further aspect, the present invention
resides in an apparatus for inspecting a moving object for
detecting a defect in the object, comprising a light
projector for irradiating light upon an inspection area of
the object from an angle between a line extending
perpendicular to a rotational axis of the object and the
rotational axis of the object, a two-dimensional CCD camera
for photographing reflected light from a fixed area of the
object, a camera controller for successively fetching
picture element data produced from said two-dimensional CCD
camera for successive frames separated in time by a
predetermined interval of time, said predetermined interval
of time being determined based on a predetermined period of
time and a thinning out value that is determine based on a
rotating speed of the object, a memory for storing the
fetched picture element data, a difference calculating
circuit for calculating differences between the picture
element data for different frames, a binary digitizing
circuit for binary digitizing the calculated differences in
accordance with a predetermined brightness threshold level,
a counter for counting a number of the differences which
have one of two binary values, and a main controller
including means for adjusting the thin~ing out value and
the predetermined brightness threshold level for said
binary digitizing circuit in re~ponse to a speed signal
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representative of a speed of the rotating or moving object
and means for counting a number of the differences which
have one of two binary values, and means for comparing the
count number with a predetermined number to determine the
presence or absence of a defect in the object.
The above and other objects, features and
advantages of the present invention will become apparent
from the following description and the appended claims,
taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of a defect detecting
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apparatus to which the present invention is applied;
FIG. 2 is a diagrammatic representation
illustrating a defect detecting method according to the
present invention;
FIG. 3 is a plan view showing a relationship
between a bottle and an inspection window in a detecting
operation in the method illustrated in FIG. 2;
FIG. 4 is a diagrammatic view illustrating a
picture image for one frame of a two-dimensional CCD
camera and analog waveforms in brightness level obtained
along a certain line of the picture image; and
FIGS. 5(A), 5(B) and 5(C) are flow charts
illustrating operation of the defect detecting apparatus
of FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring first to FIG. 2, there is illustrated
a defect detecting method to which the present invention
is applied. A transparent or translucent bottle 1 which
is an object for inspection is transported along a guide
rail 2 to an inspection window 4 (FIG. 3) formed in a
table 3. At the position of the inspection window 4,
light is irradiated from a light pro~ector 6 upon the
bottle 1 while the bottle 1 is being rotated at a fixed
speed by a drive disk 5. The light profector 6 is
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connected to a halogen light source 8 by way of an
optical fiber 7 and pro~ects light from the halogen
light source 8 in a little obliquely downward direction
toward a bottom portion of the bottle 1. Below the
inspection window 4, a two-dimensional CCD camera 9 is
installed such that an optical axis thereof makes a
predetermined angle with respect to an optical axis of
the light pro~ector 6. The two-dimensional CCD camera 9
photographs, through the inspection window 4 of the
table 3, a portion of the bottom of the bottle 1
illuminated with light from the light pro~ector 6.
Referring now to FIG. 4, there is shown, in a
rectangular screen, a picture image for one frame
photographed by the two-dimensional CCD camera 9 at a
point Tl of time. In the arrangement shown in FIG. 2,
the two-dimensional CCD camera 9 photographs only part
of the bottom of the bottle 1, and a white picture image
10 originates from reflected light from a check formed
in a circumferential edge portion of the bottom of the
bottle 1 and is high in brightness. Another small white
picture image 11 originates from disturbance light from
some portion other than the check (for example,
reflected light from a portion of the table 3). A
plurality of regularly spaced black picture images 12
originate from pro~ected portions which may be provided
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on the bottom of the bottle 1 in order to lndicate a
model number and so forth of the bottle 1 in a code
system. Another black picture image 13 originates from
a design pattern provided on the bottom face of the
bottle 1. Since the direction of reflected light from
the check is instantaneously changed to a great extent
if the bottle 1 is rotated only a little as described
hereinabove, the picture image 10 originating from the
check moves, at another point T2 of time after a short
predetermined interval of time after the point T1 of
time mentioned hereinabove, to a great extent as
indicated by a broken line in the photographing screen
of the two-dimensional CCD camera 9 while the picture
image 11 originating from disturbance light from any
other portion than the check little moves.
Referring back to FIG. 2, a picture image
processing unit 14 is connected to the two-dimensional
CCD camera 9. Picture element data produced from the
camera 9 are accepted by the picture element processing
unit 14 for each one frame and stored into a memory not
shown of the picture element processing unit 14. The
picture element data thus stored in the memory are
thereafter processed as hereinafter described. A
monitoring television set 15 in the form of a cathode
ray tube is connected to the picture image processing
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unit 14 so that a picture image accepted into the
picture image processing unit 14 can be displayed at any
time on the television set 15.
The picture image processing unit 14 has such
general construction as shown in FIG. 1. Referring to
FIG. 1, a large number of picture element data for one
frame obtained from the two-dimensional CCD camera 9 are
inputted to a camera controller 16 for each one frame.
Thus, picture element data are successively inputted to
the camera controller 16, for example, for a total of
115 frames for one full rotation of the bottle 1 at a
time interval of a fixed short time t and stored into a
memory not shown therein. Picture element data for one
frame designated by a main controller 19 are outputted
from the camera controller 16 and stored once into a
buffer memory 17, and differences of different picture
element data for a next designated one frame which are
inputted after an interval of time of t x k after the
certain point of time are calculated at a difference
calculating section 18. It is to be noted that k is a
thinning out value and is set in such a manner as
hereinafter described by the main controller 19 which
has a CPU (central processing unit) not shown therein.
Here, the reason why differences between picture image
data for two frames obtained at different times
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different by t x k are calculated is that it is intended
to extract only such picture image 10 as shown in FIG. 4
which originates from a check of a bottle.
In particular, referring to FIG. 4, a picture
element output of the two-dimensional CCD camera 9 is
taken in the form of an analog waveform along a straight
line A-A of the rectangular photographing screen at
different rotational positions of the bottle 1 and is
shown in waveform diagram in a corresponding
relationship with the picture image below the
photographing screen. Thus, at the point Tl of time at
which the picture image 10 originating from the check is
at a full line position, the waveform presents a high
level or peak only at a portion thereof which
corresponds to the picture image 11 originating from
disturbance light. On the other hand, at the point T2
of time after the interval of time t x k after then, the
picture image 11 originating from disturbance light
moves little, but the picture image 10 originating from
the check has been moved to and is now at a broken line
position, and consequently, the analog waveform then
exhibits high levels or peaks at a portion thereof which
corresponds to the picture image 11 originating from
disturbance light and another portion which corresponds
to the picture image 10 originating from the check.
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Thus, if a difference between the brightness values at
the point Tl of time and the point T2 of time is taken,
then the peak at the portion corresponding to the
picture image 10 originating from the check remains, but
the other peak at the portion corresponding to the
picture image 11 originating from disturbance light is
cancelled.
The reason why differences are taken between
picture image data for two frames obtained at different
times different by the interval of time t x k is that,
when the bottle 1 is rotated at a very high speed, such
calculation of differences between each successive ones
of the total of 115 frames for one full rotation of the
bottle 1 may not be performed, and ln order to eliminate
such a possible circumstance, different frames different
more than one frame distance are selected for such
calculation of differences. The value of the thinning
out value k is thus determined in response to a speed of
rotation of the bottle 1 such that, while the speed of
rotation of the bottle 1 rises, the interval of time
t x k may not be varied significantly.
Referring back to FIG. 1, the differences in
picture element data calculated at the difference
calculating section 18 are then binary digitized for
each picture element by a binary digitizing section 20
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with reference to a certain level of brightness or
threshold level. In other words, a certain brightness
level is determined as a reference or threshold level,
and picture element data are divided into two groups of
white and black such that, if the picture element data
are equal to or higher than the certain brightness
threshold level, then they are determined as white (1 in
binary digital value), but if they are lower than the
predetermined brightness threshold level, then they are
determined as black (O in binary digital value). Such
binary digitization is performed successively for all of
picture elements for one frame. Further, the level H
serving as the reference level for binary digitization
is automatically ad~usted in response to a speed of
rotation of the bottle 1 by the main controller 19. The
reason is that, when the speed of rotation of the bottle
1 is high, the amount of incidence light to the two-
dimensional CCD camera for photographing one frame and
hence output levels of individual solid-state image
pickup elements are low correspondingly.
Since the picture image 10 originating from the
check can be regarded as an aggregate of picture
elements having higher brightness values than the
reference brightness level for binary digitization and
likely appears at any of particular locations of the
2 ~ 6
rectangular photographing screen of FIG. 4 due to the
fact that such check likely appears at any of particular
locations of the bottom or body of a bottle, the
rectangular photographing screen of FIG. 4 is dlvided
into first to n-th window areas W~, W2, ... and Wn where
the picture image 10 of a check is apt to appear, and a
number of those of picture elements which are determined
as white by binary digitization (defect picture
elements) is counted individually for each of the window
areas W~, W2, ... and Wn. Thus, it can be presumed
that, if the number of such defect picture elements in a
window area is greater than a predetermined value, then
a check is present in the window area.
Thus, data representative positions of
individual picture elements in a window area are stored
into a window memory 21 in accordance with an
instruction from the main controller 19, and only those
of binary data of white from the binary digitizing
section 20 which belong to the window area pass through
a gate circuit 22 and are thus counted by a counter 23.
Consequently, such count value of the counter 23
represents a number of defect picture elements in the
window area, and in case the count value is higher than
a fixed level, the main controller 19 determines that
there is a check in the bottle 1 and outputs, by way of
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an interface 24, an excluding signal to the handling
machine 30 to exclude such defective bottle 1 from the
transporting line. The main controller 19 further
controls an inspection result display unit 25 to display
a number of such defective bottles, a defective location
and so forth thereon.
Picture element data for each one frame fetched
into the camera controller 16 are stored in digital
amount into a display memory 26 in a predetermined
period set by the main controller 19 and are then
converted into a video signal by a digital/video signal
converting section 27 so that they are reproduced by and
displayed on the monitoring television set 15. Initial
set values and so forth necessary for inspection are
inputted in prior to the main controller 19 by way of an
interface 29 from a keyboard 28 while a reproduced image
on the television set 15 is being observed by an
operator.
An inspection timing signal, a bottle presence
signal representing that a bottle is present at a
predetermined inspection position, a speed signal
representing a speed of rotation of such bottle and so
forth are inputted from a handling machine 30 to the
main controller 19. The thinning out value k and the
reference level H for binary digitization described
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above are adJusted in accordance with the thus inputted
speed signal. As already known, the handling machlne 30
performs various operations including transporting a
bottle 1 and rotating the bottle 1 at the lnspection
position by means of the drive disk 5 as described
above. Alternatively, a speed of rotation of the bottle
1 may be measured by counting a number of inspection
timing signals received by the main controller 19 for a
unit period of time.
Operation of the main controller 19 is
illustrated in FIGS. 5(A) to 5(C). Referring first to
FIG. 5(A) in which a main routine is shown, various
initializing operations are executed first at step 50,
and then at step 51, such thinning out value k and
reference level H for binary digitization as described
above are set in accordance with a speed signal from the
handling machine 30 or a speed measured from inspection
timing signals. Then at step 52, a first subroutine
shown in FIG. 5(B) is executed, and then at step 53,
conditions of input keys of the keyboard 28 are checked,
whereafter the control sequence returns to step 51.
When the first subroutine shown in FIG. 5(B) is
entered, it is ~udged first at step 55 whether or not
there is an inspection timing signal, and if there is no
inspection timing signal, then conditions of the input
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keys of the keyboard 28 are checked at step 56,
whereafter the control sequence returns to step 55 to
repeat a similar sequence of operations. On the
contrary if there is an inspection timing signal at step
55, then the control sequence advances to step 57, at
which counting of a counter for measuring an inspection
time is started, and then to step 58, at which it is
~udged whether or not there is a bottle presence signal,
in short, whether or not a bottle 1 is present at the
inspection position. Then, if a bottle 1 is present,
then all re~ection flags are reset at step 64, and then
a skip flag is set at step 65. The skip flag is
provided so that picture element data for a first one
frame received at first from the camera controller 16
shown in FIG. 1 may be stored into the buffer memory 17.
Thus, the skip flag is set in the first control cycle.
Subsequently, a second subroutine shown in FIG. 5(C) is
executed.
Referring now to FIG. 5(C), after the second
subroutine shown is entered, it is ~udged first at step
72 whether or not the skip flag is in a set state.
Since the skip flag is in a set state in the first
control cycle, the control sequence advances to step 77,
at which the counter 23 of FIG. 1 is reset, and then to
step 78, at which the skip flag is reset, whereafter the
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control sequence returns to the first subroutlne of
FIG. 5(B).
Since the skip flag is in a reset state at step
72 in the second or succeeding control cycle, the
control sequence now advances to step 73, at which a
number of defect picture elements in the first window
area W~ is counted by the counter 23 as described
hereinabove, and then to step 74, at which the count
value is compared with a fixed excluding level set for
the first window area Wl. Then, a ~udgment for
allowance or re~ection for the window area W~ is made at
step 75 in accordance with a result of such comparison.
In case the ~udgment is re~ection, a re~ection flag is
set for the window area Wl at step 76, but in the case
of allowance, the control sequence advances to a step
for the second window area W2 skipping the step 76.
Then, similar operations to those at steps 73 to 76 are
repeated to the last n-th window area Wn, and after
completion of such ~udgment, the control sequence
returns to the first subroutine of FIG. 5(B) by way of
the steps 77 and 78 described above.
After the control sequence returns to the first
subroutine of FIG. 5(B), presence or absence of an
inspection timing signal is determined at step 67, and
if there is an inspection timing signal, then conditions
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of the input ke~s are checked at step 68, whereafter the
control sequence returns to step 67. If there is no
inspection timing signal at step 67, then the main
controller 19 checks all of the re~ection flags for the
windows W~ to Wn and determines, when all of the
re~ection flags are not in a set state, that the bottle
1 is allowable, but determines, when at least one of the
re~ection flags is in a set state, that a check is
present at a corresponding window and accordingly the
bottle 1 is to be re~ected. Then, a result of the
determination is outputted to the handling machine 30 at
step 70. In particular, when the determination at step
69 is re~ection, the main controller 19 outputs, by way
of the interface 24, an excluding signal to the handling
machine 30 to exclude such defective bottle 1 from the
transporting line. Then, the inspection time measuring
counter is stopped at step 61, and then the thinning out
number k and the reference level H for binary
digitization are newly set at step 62, whereafter the
control sequence returns to the main routine of
FIG. 5(A).
In case there is no bottle presence signal at
step 58, presence or absence of an inspection timing
signal is determined at step 59, and if there is an
inspection timing signal, then conditions of the input
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keys of the keyboard 28 are checked at step 60,
whereafter the control sequence returns to step 58, but
on the contrary if there is no inspection timing signal,
then the inspection time measuring counter is stopped at
step 61 as described hereinabove, whereafter the control
sequence returns to the main routine of FIG. 5(A) by way
of the step 62.
It is to be noted that, while presence or
absence of a check at a bottom portion of a bottle 1 is
detected while the bottle 1 is being rotated in the
embodiment described above, otherwise presence or
absence of a check at any portion other than such bottom
portion can be inspected. Further, it is also possible
to inspect a bottle 1 while the bottle 1 is being moved,
for example, along a horizontal path. Further, presence
or absence not only of a check but also of a white
foreign article can be inspected. Furthermore, the
ob~ect for inspection is not limited to a bottle, and
the present invention can be applied also to inspection
of a glass, a transparent or translucent plastic vessel
and so forth.
Having now fully described the invention, it
will be apparent to one of ordinary skill in the art
that many changes and modifications can be made thereto
without departing from the spirit and scope of the
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inventlon as set forth herein.
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